In the drilling and completion industry, the formation of boreholes for the purpose of production or injection of fluid is common. The boreholes are used for exploration or extraction of natural resources such as hydrocarbons, oil, gas, water, and alternatively for CO2 sequestration. It is often necessary to isolate a zone within the borehole or within a tubular structure within the borehole, such as a casing or tubing string. Zone isolation is typically performed using packers which perform well for such a purpose. The packer is typically a flexible, elastomeric device that has a smaller initial outside diameter that then expands externally to seal to the borehole or outer tubing, thus separating the annulus between a tubular that supports the packer and the borehole or outer tubing into separate zones. Packers may be set through inflation or compression and are useful in both production and injection operations where zone isolation is useful. Some packers are also re-settable allowing for multiple uses and trips within the borehole.
One situation in which zonal isolation is useful is steam assisted gravity drainage (“SAGD”). SAGD is a process for the recovery of heavy oil in which two parallel adjacent horizontal boreholes are drilled in a formation. The upper borehole (an injection well) injects steam to the formation and reduces the viscosity of the heavy crude oil or bitumen, allowing it to flow down to the lower borehole (a production well) that collects the heated crude oil or bitumen.
The art would be receptive to alternative devices and methods for isolation within a borehole, as well as alternative devices and methods useful in SAGD.